Even if it is a bright and sunny day, this is still a great place to spend an afternoon. You won't miss the beautiful architecture outside, but its the paintings that are excellent. I'm no expert, but I always visit the portraits by Allan Ramsay of his first and second wives. Gallery is on Queen Street at the corner of North St Andrew Street / Dublin Street, take the tram to St Andrew's Square or York Place. Its free entry but please consider leaving a donation as this really is something special.